Hey Ulrike, you'll have to create a different segment for every type of subscriber that you would have. To be honest, in this type of situation where someone might be using multiple products and you're potentially looking to send different emails based on this, then segmentation probably isn't your best bet.
The idea of segmentation is that each person can only fall into one category in a top-down cascade-type of filtering. With 6 products where someone could use multiple products, and unless your first category is "multiple products" followed by all of the individual products, then you'd have to create a different segment for every possible combination of your products.
For dynamic text, you can present different text within the email based on what segment someone is in, but again -- the idea of segments is that a person can only be in a single segment of each segmentation. So they can't be a in product 2 AND product 6. At that point, they could only be in 2 or 6 (whichever was listed first), or a "multiple products" segment.
Hope this helps a bit.